Phenotypic plasticity and optimal timing of metamorphosis under uncertain time constraints
Phenotypic plasticity and optimal timing of metamorphosis under uncertain time constraints
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DOI：
10.1007/s10682-006-0017-9
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发表时间：
2007-01-01
影响因子：
1.9
通讯作者：
Roedel, Mark-Oliver
中科院分区：
文献类型：
--
作者：
Rudolf, Volker H. W.;Roedel, Mark-Oliver
生活史理论认为，变态的最佳时机应该取决于生长条件和个体发育的时间限制。目前的模型不能对短暂栖息地中的物种做出可靠的预测，在这些栖息地中，个体经常面临随着时间的推移而增加的死亡风险，因为这些模型假设了时间不变的死亡率（即，每日死亡率保持不变）和固定的季节。我们研究了可塑性的生长，发育和身体质量在变态的树洞繁殖青蛙Phrynobatrachus guineensis在一个不可预测的时间限制在现场和对照实验沿着一个固定的密度和食物梯度的蝌蚪。平均质量和年龄在变态的同胞与人均食物水平呈正相关。根据我们的研究结果，我们开发了一个简单的模型，根据时间依赖性死亡率的最佳时间变态显示，发展速度不仅调整到生长条件，但也随时间变化的死亡率。增加的死亡率代表了有利于减少幼虫期的时间限制，但由于它是基于生存的概率，它允许在发育时间和质量之间进行权衡。我们将此模型扩展到不同类型的时间限制，并表明它可以预测记录的反应规范的范围。不同物种之间的年龄和质量的相关性在变态可能已经演变，由于其随时间变化的死亡率的差异。
Life-history theory suggests that optimal timing of metamorphosis should depend on growth conditions and time constraints under which individuals develop. Current models cannot make reliable predictions for species in ephemeral habitats where individuals often face an increasing mortality risk over time because these models assume time-invariant mortality rates (i.e., daily mortality rates remain constant) and fixed seasons. We examined the plasticity of growth, development, and body mass at metamorphosis in tadpoles of the tree-hole breeding frog Phrynobatrachus guineensis in relation to an unpredictable time constraint in the field and in controlled experiments along a fixed density and food gradient. Mean mass and age at metamorphosis of sibships were positively correlated with per capita food level. Based on our results, we developed a simple model of the optimal timing of metamorphosis under time-dependent mortality rates showing that development rates are not only adjusted to growth conditions but also to time-variant mortality rates. The increasing mortality rate represents a time constraint that favors a reduced larval period, but because it is based on probabilities of survival it allows a trade-off between development time and mass. We extend this model to different types of time constraints and show that it can predict the range of documented reaction norms. Differences between species in the correlation of age and mass at metamorphosis may have evolved due to differences in their time-variant mortality rates.